High-temperature temperature fuse device

ABSTRACT

There is provided a high-temperature temperature fuse device in which a temperature fuse inserted between two terminals is blown at a temperature higher than a predetermined value to break the electric connection between the terminals, and the fuse is made of a noble metal such as gold or its alloy.

United States Patent [1 1 Soda 1 Sept. 16, 1975 HIGH-TEMPERATURE TEMPERATURE FUSE DEVICE [75] lnventor: Kazuya Soda, Takahama, Japan Assignee: Nippondenso Co., Ltd., Japan Filed: Sept. 5, 1973 Appl. No.: 394,476

[30] Foreign Application Priority Data Sept. 8, 1972 Japan 47-90676 Sept. 14, 1972 Japan 47-92597 7 Nov. 10, 1972 Japan 47-ll3260 US. Cl. 337/158; 337/159; 337/290; 337/295; 337/296 Int. Cl. H0lh 85/04 Field of Search 337/159, 160, 290, 295, 337/296, 158, 416; 75/165, 172 R, 173 R [56] References Cited UNITED STATES PATENTS 2,703,352 3/1955 Kozacka 337/290 X 2,809,257 10/1957 Swain 2,939,934 6/1960 Kozacka Primary Examiner.l. D. Miller Assistant Examiner-Fred E. Bell Attorney, Agent, or Firm-Cushman, Darby & Cushman ABSTRACT 5 Claims, 4 Drawing Figures PATENIED s5? 1 6 [STE FIG.

FIG.

FIG. 4

HIGH-TEMPERATURE TEMPERATURE FUSE DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature temperature fuse device, more particularly a hightemperature temperature fuse of the type which is installed in an automobile exhaust gas purifier; whereby when the temperature within the exhaust gas purifier rises abruptly or excessively due to for examplea trouble in the engine, the electric circuit is broken to stop the delivery of fuel to the engine, the engine ignition 'circuit is interrupted to stop the engine, or the by-pass valve, air pump lamp or buzzer is actuated so as to protect the exhaust gas purifier and other component parts of the engine.

2. Description of the Prior Art While, in the past, no devices of the above type have been additionally provided in the known automobile exhaust gas purifiers, it is expected that in the future, such a highternperature temperature fuse device will be used as a safety device for exhaust gas purifiers and that the required melting temperature for such a temperature fuse device is usually in the range from 700 to 1300C and this melting temperature depends on the kind and type of exhaust gas purifier and other factors. Therefore, fuse materials selected for such fuse devices must always meet these requirements and they must also perform their functions satisfactorily. While various fuse materials may meet these requirements, it has been found by the inventor that noble metal groups (e.g., pure noble metals or alloys thereof and alloys of noble metals with base metals) lend themselves to be excellent fuse materials which possess satisfactory lasting quality such as corrosion resistance and resistance to oxidation and which are capable of performing the required function of positively melting at a predetermined temperature.

SUMMARY OF THE INVENTION It is therefore the object of the present invention to provide a high-temperature temperature fusedevice which comprises a fuse made of a material consisting of a noble metal type and which thus possesses a sufficient durability and positively melts at a predetermined temperature.

A remarkable advantage of the novel hightemperature temperature fuse device of this invention is that it is capable of positively melting at a predetermined temperature, highly durable in high-temperature service. and easy to manufacture since it requires no hermetically sealed structure.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal sectional view showing an embodiment of a high-temperature temperature fuse device according to the present invention.

FIG. 2 is a longitudinal sectional view showing another embodiment of the high-temperature temperature fuse device according to the present invention.

FIG. 3 is an enlarged longitudinal sectional view showing the upper end portion of the device shown in FIG. 2.

FIG. 4 is an enlarged longitudinal sectional view showing the upper end portion of a high-temperature temperature fuse device of the type in which the connecting wires are eliminated.

.- DESCRIPTION OF THE PREFERRED EMBODIMENT The construction of the first embodiment of this invention will be described with reference to FIG. 1, in which numeral 1 designates a connecting coil made of for example nichrome, 2 a temperature fuse constituting the principal part of the high-temperature temperature fuse device, 3 an insulating tube which provides a blowing space for the fuse 2 and in which the fuse 2 is disposed. Numeral 4 designates a center holding pin made of for example nichrome and having one end secured to the fuse 2. Numeral 5 designates a heat resisting protection tube made of for example stainless steel, 6 an inorganic insulating filler such as ceramic filled in the tube 5 to insulate the tube 5 from the center holding pin 4. Numeral 7 designates a housing made of a heat resisting material such as stainless steel and securely mounted near the centralportion of the tube 5. Numeral 8 designates a layer of special glass for hermetically sealing the upper portion of the tube 5, 9 an insulating ring. 10 a terminal.

The manufacturing.processof the above-constructed fuse device of this invention is as follows. Firstly, the temperature fuse 2, the coil 1 andthe center holding pin 4 welded together by spot welding, for example, and then they are enclosed by the insulating tube 3. The thus welded coil 1 is welded to the heat resisting protection tube 5 by argon arc welding. for example. Thereafter, the inorganic insulating filler 6 is filled in the heat resisting protection tube 5 and the special glass layer 8 and the insulating ring 9 are then fixedly mounted. After the terminal 10 is connected to the center holding pin 4 by soldering, for example, the heat resisting protection tube 5 and the housing 7 are welded together by plasma arc welding, for example, to complete the high-temperature fuse device of the construction shown in FIG. I.

In an exemplary application of the device of this invention, the fuse device is mounted by the housing 7 in an exhaust gas purifier (e.g., a manifold reactor or a catalytic converter) so that the temperature fuse 2 in the protection tube 5 is completely inserted within the purifier. The ends of the housing 7 and the terminal 10 are connected in series with the electric circuit of the ignition system of the fuel pump or they are connected to the circuit of the by-pass valve, air pump. lamp or buzzer. Accordingly, when the internal temperature of the exhaust gas purifier rises abnormally due to for example a trouble in the engines. the temperature fuse 2 is blown to break the electric circuit of the ignition system or the fuel pump to urgently stop the engine or actuate the by-pass valve, air pump, lamp or buzzer.

The following Tables I and 2 show the results of the measurements of the initial melting temperatures and the melting temperature subsequent to the endurance tests on the high-temperature temperature fuse devices made in accordance with the embodiment of this invention and employing various temperature fuses having the compositions defined according to the teachings of this invention.

In the measurements of the initial melting temperature shown in Table I, each of the high-temperature temperature fuse devices according to the present invention was installed in a manifold reactor exhaust gas Table 2 Composition of Melting temperature Average Temperahigh-tempera- Exposure measured subsequent value ture ture temperatempcrato endurance test C) range ture fuse ture (C) (C) ("Cl Au(X3)-Pd(l7) lI()U|l5() I215. I233. 1228 1225 I8 Au IOU) 900-950 NH). I026. I030 1025 ll purifier. Then, the temperature in this exhaust gas purifier was raised at the rate of 20C/min and the temperature at which the temperature fuse melted was measured with a L platinum-platinum palladium thermocoupleThe dimensions of the temperature fuse 2 in the tested high-temperature temperature fuse devices of this invention were as follows: temperature fuse diameter 0.5 mm. temperature fuse length 10 mm, insulating tube inner diameter 2.5 mm. insulating tube outer diameter 4.5 mm, and insulating tube length mm. The temperature fuses used in all 'other devices tested had the same dimensions.

In each of these fuse devices, the hermetic seal provided by the special glass layer 8 was not complete to permit the external air to reach the temperature fuse 2 through the opening between the insulating ring 9 and the'heat resisting protection tube 5. This was the same in all the sample devices and therefore the temperature fuse 2 was more or less in contact with the external air.

present invention showed the initial melting temperatures which well conformed to the theoretical values and which were excellent with small variations in the measured temperatures. This relay means that the device of thisinvention can positively melt at a predeter mined melting temperaturev Further, the melting temperaturecan be changed as desired by changing the composition of the temperature fuse 2.

In the measurements of Table 2 showing the melting temperatures of the temperature fuses measured subsequent to the endurance tests. the high-temperature temperature fuse devices of this invention was installed in the manifold reactor exhaust gas purifier and each of the temperature fuse devices was heated to the exposure temperature shown in Table 2, to which temperature the device was exposed and rested for 1000 hours and its melting temperature was measured in the same conditions as in the case of Table I.

Table 1 Composition of Measured initial Average Temperahigh-tcmperaturc melting temperavalue ture temperature fuse ture range (C) Au as) Pdtl?) 055.124.1230 I245 4l a 1265.17.53. Au(94)-Pd46) 1173.1i5x 11so 117s 34 1192,1175 40 Au 100) I035. I038. I023. I043 37 i |05s lost) Au (35) 9x2. 1003. 100*). was 42 AgHiS) 967.970 Ag 100 955. 9424. 960. 94s 2s In this Table l, the parenthesized numbers for the constituents indicate the percentages by weight.

As will be apparent from Table 1, the hightemperature temperature fuse devices according to the so In Table 2 above, the parenthesized numbers for the constituents indicate the percentages by weight.

It will be seen from Table 2 that even after the endurance tests in which the temperature fuse 2 was allowed to rest at the elevated temperature for 1000 hours with the temperature fuse 2 left more or less in contact with the external air, the measured melting temperatures of the devices of this invention satisfactorily conformed with their initial melting temperatures. Moreover, the variations of the measured melting temperatures are small and their durability is also very great.

For comparison, the results of the similar measurements made on the temperature fuses made of constituent elements other than the noble metals are shown in Tables 3 and 4. Table 3 shows the measured initial melting temperatures and Table 4 shows the results of the endurance tests made on these temperature fuses. The method of measurement and the method of endurance test were the same as in the cases of Tables 1 and 2, respectively.

After 20 8t) hours the same results as above.

It will be seen from Tables 3 and 4 that while the measured intial melting temperatures conformed sufficiently with the theoretical values and were generally satisfactory with small variations in the measured melting temperatures. the exposure to the elevated temperatures resulted in the complete oxidation and faulty fuse in all of the five samples after several tens of hours due to the fact that the temperature fuse was more or less in contact with the external air.

Referring now to FIGS. 2 and 3, the construction of another embodiment of the high-temperature temperature fuse device according to the present invention will be described. In FIGS. 2 and 3, the identical reference numerals as used in FIG. I designate the identical or similar component parts Numeral 7 designates the housing made of a heat resisting metal such as stainless steel. The housing 7 is fixedly mounted on the protection tube 5 and it is provided with a tool engaging hexagonal portion 7a and a mounting threaded portion 7b. The temperature fuse 2 and connecting wires 11 are disposed in the insulating tube 3. Numeral l2 designates a ceramic fixing material for securing the insulating tube 3 in place and hermetically sealing the blowing space. l I

In the second embodiment of the high-temperature temperature fuse device of this invention constructed as described above, the terminal 10, the center holding pin 4, the connecting wire 11, the temperature fuse 2, the connecting wire 11, the connecting coil 1, the protection tube 5 and the housing 7 are electrically and mechanically interconnected by welding or soldering. Therefore, it is possible to detect whether the temperature fuse 2 is faulty or'not by detecting the electric conduction between the housing 7 and the terminal 10. In

this case since, in this embodiment of the hightemperature temperature fuse device of this invention, the connecting wire 11 is connected between the temperature fuse 2 and the connecting coil 1 and between the fuse 2 and the center holding pin 4 and this conneeting wire 11 is made ofa platinum group metal such as platinum or its alloy, e.g., platinum, rhodium, palladium or iridium which does not react with the coil 1 and the pin 4 of the temperature fuse 2 at the normal temperature. Thus, the melting temperature does not change over a long period of time. Of course, the melting point of the connecting wire 11 should be suffieiently higher than that of the temperature fuse 2 and it should be chemically stable at the normal temperature. The above-mentioned platinum and its alloys meet these properties.

The actual values of the initial melting temperatures measured on the high-temperature temperature fuse device according to this embodiment will be explained. The samples used consisted of high-temperature temperature fuse devices in which the temperature fuse 2 of 0.5 mm diameter and 10 mm length and having the platinum connecting wire 11 of 0.5 mm diameter and 2 mm length secured at each end thereof by welding was disposed in the insulating tube 3 of 2.5 mm inner diameter, 4.5 mm outer diameter and 15 mm length. Each sample device was installed in an automobile exhaust gas purifier, ie, a manifold reactor and the temperature in the manifold reactor was raised at the rate of 30C/min. The melting temperatures measured on these sample devices with a platinum-platinum paradium thermocouple are shown in the following Table 5.

In the above Table 5, the parenthesized numerical values in the composition of the temperature fuses indicate the percentages by weight. This is the same in the following Tables 6 and 7. i

As will be seen from Table 5 above, variations of the measured melting temperatures on each of the sample devices are small and thus satisfactory for practical uses.

The results of the melting temperature tests conducted subsequent to the endurance tests on the hightemperature fuse devices in accordance with the second embodiment are shown in Table 6. The sample devices used were of the same construction as in the case of Table 5. Each of these sample device was installed in the manifold reactor and the internal temperature of the manifold reactor was kept at the settemperature indicated in Table 6 for 1000 hours. After the endurance test conducted for the period of 1000 hours, the

melting temperature was measured by the same mea- Set temperature Average Tempevalue rature C range Composition of temperature fuse Melting temperature measured after endurance ICSI Number of samples.

l050-l I00 I295, l300.

I295 I065. I065.

As will be seen from the above Table 6, it was 'confirmed that the high-temperature temperature fuse devices according to this embodiment showed no abnormality such as faulty fuse and breaking subsequent to the endurance tests for 1000 hours and that the measured melting temperatures were practically the same with the initial melting temperatures.

The results of the endurance tests showed that after the many hours of heating at the temperatures ranging from 950 to 1 C, the tested sample devices showed no abnormality such as the variation of the melting temperature due to the formation of alloys and any other changes in the quality of the materials.

For comparison, Table 7 shows the results of the melting temperature measurements conducted subsequent to the endurance tests on the devices having the construction of FIG. 4 in which no connecting wires 11 were provided. The conditions for the endurance tests and the measurement conditions were the same as in the ease of Table 2. The set heating temperature was in the range from l050 to ll00C for the device employing the temperature fuse having the composition:

7 Au (x3) Pd 17 l050 a) 1 100C for the composition: Au (94) Pd (6) and 900 to 950C for the composition: Au 100). The initial melting temperatures of the devices of the construction shown in FIG. 4 were quite similar to those shown in Table 1.

Table 7 Average value (C) Composition of temperature fuse Temperature range As will be seenfrom the above Table 7'. the melting temperatures subsequent to the endurance tests were lower than the initial melting temperatures by about 50 to l00C and the ranges of variations of the measurements were also larger.

Table t shows the results of the grain growth on heating and the results of the endurance test conducted on the samplehigh-temperature temperature fuse devices in accordance with the present invention which were equipped with various temperature fuses having different compositions. In the measurement of the grain sizes shown in Table 8, drawn wires of 1 mm diameter and length were used as specimens and they were heated up to 1000C in an electric furnace. The solution used for etching the specimens for microscopic examination consisted of a boiled mixture prepared by mixing nitric acid, hydrochloric acid and water at the ratio of 1:5:6. The grain sizes were measured by the following method. Namely, each of the specimens with the structure revealed in the previously mentioned manner was photographed through a microscope and the average size of the grains contained in the rectangular photograph was measured. In other words, the number N of the grains contained completely within the rectangular photograph (photographed area 90 X 65 mm) and the number n of the grains joining the boundary lines of the rectangular were measured and the average grain diameter D was calculated according to the following formula:

In the above Table 8. the numbers in the column for the base metal indicate the percentages of weight. This is the same with the numbers in the column for the base metal in Table 9 and Table 10, respectively. As will be seen from Table 8, the grain sizes in the specimens containing iridium, rhodium, copper and nickel are considerably small as compared to those obtained with the base metals containing no additional element. A reduced grain size indicates an improved mechanical strength (e.g.. tensile strength. bending strength and compressive strength) and this is a well known fact mentioned in literature and others. In fact, it has been found that the high-temperature temperature fuse devices constructed according to the teachings of this invention possess highly improved resistance against mechanical vibrations and shocks.

The endurance test results in Table 9 show that when the high-temperature temperature fuses, constructed according to this invention were installed in the manifold reactor exhaust gas purifier and subjected to the endurance tests at about 1000C. they showed no abnormality at the endurance goal of 1000 hours. Further. Table 10 shows the results of the endurance tests on the samples not containing iridium and other alloying elements. Three samples were prepared for each of the tested fuses and all of them showed the occurrence of abnormality. i.e., the mechanical rupture before attaining the endurance goal of 1000 hours. Further. while Table 9 shows the test results obtained on the endurance test samples for the high-temperature temperature fuse device of this invention which contained the additional elements of up to 0.03 by weight. this is done to show the test results on those samples having relatively large grain sizes, i.e., relatively low mechanical strength. The test results obtained on other samples containing the additional elements of up to 0.1 "/0 and 0.3 respectively, also showed no occurrence of abnormality.

Table 9 Endurance Test Additional element Endurance at i000 hours Number of sample Base metal Percentage of addition 0.03 7! by weight No abnormality Cu Ni lr 3 No abnormality Au (96)- Pd (4) Table 8 Average Diameter of Grains unit p.

Busc metal Au Au (U4) Pd ((1 Heating time hours hours I000 hours ll] hours IOU hours lilllll 1 hour hou rs ll3.2v

Without alloying element 0.0} /1 by weight 0.] "i by weight (1.3 "i by weight Iridium Rhodium Copper 0.03 I; by weight 0.| Z by weight 0.3 by weight Nickel IH.N l5. 14.6

32.x 1&2 2H5 38.5 34H Kill Table 10 Endurance Tests Material Sample Test result Ruptured at I83 hours Ruptured at 96 hours Ruptured at 2 l 6 hours Ruptured at I57 hours Ruptured at 386 hours Ruptured at I97 hours.

Au (96) Pd (4) perature fuse device can be provided whichpossesses a sufficient strength at high-temperatures without losing any of the superior properties inherent .to the noble metal or its alloy such as corrosion resistance and melting performance. 0

Further, the reason for limiting the amount of the additional elements between 0.01 and L0 %.is that the addition of less than 0.01 has no graingrowth preventing effect and it isalso ineffective in improving the .durabiltiy. On the other hand, the addition of more than 1.0 70 has almost the same effect on the prevention of grain growth and improvement of the durability as compared with the cases where the amount of the additional elements is less than 1.0 and moreover there is an adverse effect on the melting temperature which tends to cause variation in the desired melting temperature.

While the present invention has been described as applied to an exhaust gas purifier, the high-temperature temperature fuse device of this invention is not limited to exhaust gas purifiers, but it can be used in many other applications. Further, the noble metals referred to in the specification include gold, silver, platinum, palladium, iridium, osmium, rhodium and ruthenium.

I claim:

1. A high-temperature fuse device of the type in which a temperature fuse inserted between terminals is blown at a temperature higher than a predetermined value within the range of 700 to 1300C. to break the electrical connection between said terminals when the fuse is subjected to an excessively high temperature from outside said fuse and wherein said temperature fuse comprises a noble metal, a connecting lead wire provided at each end of said temperature fuse, and a metal which does not form an alloy with said temperature fuse and said connecting lead wire at a temperature of about 700 to 1300C., disposed between said temperature fuse and said connecting lead wire to connect said temperature fuse to said connecting lead wire.

2. A high-temperature temperature fuse device according to claim 1, wherein said temperature fuse comprises a metal selected from the group consisting of gold and its noble metal alloy, and a metal selected from the group consisting of iridium, rhodium, copper and nickel in an amount ranging from 0.01 to 1.0

3. A high temperature fuse device according to claim 1, wherein the noble metal is gold.

4. A high temperature fuse device according to claim 1 wherein the noble metal is selected from the group consisting of gold, silver, platinum, palladium, iridium,

osmium, rhodium, and ruthenium.

H 5. A high-temperature fuse device according to claim 1, wherein the connecting lead wire comprises a member of the group consisting of platinum, rhodium, palladium and iridium. I 

1. A high-temperature fuse device of the type in which a temperature fuse inserted between terminals is blown at a temperature higher than a predetermined value within the range of 700* to 1300*C. to break the electrical connection between said terminals when the fuse is subjected to an excessively high temperature from outside said fuse and wherein said temperature fuse comprises a noble metal, a connecting lead wire provided at each end of said temperature fuse, and a metal which does not form an alloy with said temperature fuse and said connecting lead wire at a temperature of about 700* to 1300*C., disposed between said temperature fuse and said connecting lead wire to connect said temperature fuse to said connecting lead wire.
 2. A high-temperature temperature fuse device according to claim 1, wherein said temperature fuse comprises a metal selected from the group consisting of gold and its noble metal alloy, and a metal selected from the group consisting of iridium, rhodium, copper and nickel in an amount ranging from 0.01 to 1.0 %.
 3. A high temperature fuse device according to claim 1, wherein the noble metal is gold.
 4. A high temperature fuse device according to claim 1 wherein the noble metal is selected from the group consisting of gold, silver, platinum, palladium, iridium, osmium, rhodium, and ruthenium.
 5. A high-temperature fuse device according to claim 1, wherein the connecting lead wire comprises a member of the group consisting of platinum, rhodium, palladium and iridium. 